JP3150218B2 - Biodegradable short fiber non-woven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable short-fiber nonwoven fabric having biodegradability, moderate hydrophilicity and hydrophobicity, and excellent mechanical strength and dimensional stability.

[0002]

2. Description of the Related Art Conventionally, nonwoven fabrics of viscose rayon short fibers obtained by a dry method or a solution immersion method, nonwoven fabrics of kipura rayon or viscose rayon long fibers obtained by a wet spunbond method, chitin, atelocollagen, etc. Various biodegradable nonwoven fabrics are known, such as a nonwoven fabric made of chemical fibers of natural products and a spunlace nonwoven fabric made of cotton. However, in these conventional biodegradable nonwoven fabrics, the mechanical strength of the constituent materials of the nonwoven fabric itself is low and hydrophilic, so the mechanical strength during water absorption / wetting is remarkably reduced. There are various problems such as a large inferior dimensional stability and a lack of thermal adhesiveness because the material itself is non-thermoplastic. On the other hand, in recent years, a biodegradable nonwoven fabric composed of thermoplastic fibers has been proposed to solve the above problem. However, this nonwoven fabric has poor hydrophilicity and is practically used in application fields where a certain water retention capacity is required. It could not be used for

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a biodegradable short fiber having biodegradability, moderate hydrophilicity and hydrophobicity, and excellent mechanical strength and dimensional stability. It is intended to provide a nonwoven fabric. In addition, the present invention has excellent mechanical properties not only under dry conditions but also under water-absorbing / wetting conditions, and has extremely small shrinkage during repeated drying / wetting, and has excellent dimensional stability. It is intended to provide a short fiber nonwoven fabric.

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention
95 to 5% by weight of short fibers made of a biodegradable thermoplastic aliphatic polyester-based polymer and 5 to 95% by weight of cellulosic short fibers are mixed, and the constituent fibers are partially thermally bonded to each other. Wherein the aliphatic polyester
Polyglycol wherein the polymer is poly (α-hydroxy acid)
Polymers composed of cholic acid and polylactic acid or their co-polymers
Or poly-3-hydroxybutyrate, poly-
3-hydroxycaprolate, poly-3-hydroxy
Butanoate, poly-3-hydroxyoctanoate,
And poly-3-hydroxyvalerate or poly
Poly (β which is a copolymer with 4-hydroxybutyrate
-Hydroxyalkanoate), or glycol and di
Polyethylene is a condensation polymer of carboxylic acid
Xarate, polyethylene succinate, polybutylene
Oxalate, polybutylene succinate, or this
Consisting of any of these copolymers, and having a melting point of
A biodegradable short-fiber nonwoven fabric characterized by a temperature of 100 ° C. or higher .

Hereinafter, the present invention will be described in detail. Biodegradable thermoplastic aliphatic polyester in the present invention
The polymer is a poly (α-hydroxy acid) polyglycol.
Polymers composed of cholic acid and polylactic acid or their co-polymers
Or poly-3-hydroxybutyrate, poly-
3-hydroxycaprolate, poly-3-hydroxy
Butanoate, poly-3-hydroxyoctanoate,
And poly-3-hydroxyvalerate or poly
Poly (β which is a copolymer with 4-hydroxybutyrate
-Hydroxyalkanoate), or glycol and di
Polyethylene is a condensation polymer of carboxylic acid
Xarate, polyethylene succinate, polybutylene
Oxalate, polybutylene succinate, or this
It consists of any of these copolymers. In the present invention, the above-mentioned thermoplastic polymer having biodegradability, if necessary, for example, various additives such as matting agents, pigments, light stabilizers, heat stabilizers, antioxidants, etc. Can be added in a range that does not impair the effects of the present invention.

[0006] In the present invention, the thermoplastic aliphatic polyester-based polymer having biodegradability is 1 00 ° C. or higher melting point. When a nonwoven fabric is formed using the short fibers made of this polymer , the nonwoven fabric can be provided with a certain heat resistance.

In the present invention, the short fibers comprising the biodegradable thermoplastic aliphatic polyester-based polymer are as follows:
It is composed of the above polymer, but in addition to those composed of a single biodegradable polymer, two or more types of biodegradable polymers are concentric sheath-type or eccentric sheath-core type Alternatively, composite short fibers having various composite forms such as a side-by-side type may be used. In addition, the short fibers in the present invention may have various irregular cross-sections such as a triangle or a star or a hollow cross-section in addition to a normal circular cross section. In the present invention, the short fiber has a single fiber fineness of 0.3 to 20 denier, and if the single fiber fineness is less than 0.3 denier, the card passing property when producing a card web is inferior. , Single fiber fineness is 20
If the denier is exceeded, the formation of the obtained nonwoven fabric becomes coarse and the quality is inferior.

In the present invention, the cellulosic staple fiber is a natural fiber such as cotton and hemp, and a chemical fiber composed of various rayon fibers and natural products such as chitin. It is not particularly limited as long as it has fibers.

The biodegradable short-fiber nonwoven fabric according to the present invention comprises:
95 to 5% by weight of the short fibers made of the polymer and 5 to 95% by weight of the cellulosic short fibers are mixed. In this nonwoven fabric, if the short fibers made of the polymer exceed 95% by weight, the water retention of the nonwoven fabric is inferior. On the other hand, if the short fibers are less than 5% by weight, not only the dimensional stability of the nonwoven fabric is deteriorated, but also the heat bonding becomes poor. Properties are not expressed, and none of them is preferable.

[0010] The nonwoven fabric of the present invention is one in which constituent fibers thereof, that is, the biodegradable staple fibers, and the biodegradable staple fiber and the cellulosic staple fiber are partially thermally bonded. . This partial thermal bonding
It is formed by a known heat bonding process, whereby the form of the nonwoven fabric is maintained, and the nonwoven fabric exhibits excellent mechanical strength and dimensional stability.

The nonwoven fabric of the present invention preferably has a basis weight of 20 g / m ² or more. In this nonwoven fabric, if the basis weight is less than 20 g / m ² , the handling property is inferior in the production of the nonwoven fabric, which is not preferable.

The nonwoven fabric of the present invention can be manufactured by the following method. First, according to a conventional method, the thermoplastic aliphatic polyester polymer having biodegradability is melt-spun, and the spun yarn is cooled using a cooling air stream or cooling water and then once wound up. To a non-stretched yarn, or continuously without winding, cold- or hot-stretching it in one or two or more stages, and then machine the resulting stretched yarn using, for example, a stuffing box. A short fiber is obtained by applying a crimp or applying a crimp by a heat shrinking treatment and cutting it into a predetermined length. The spinning temperature at the time of melt spinning depends on the melting point and the degree of polymerization of the polymer used.
The temperature is desirably 20 to 300 ° C. Spinning temperature is 120
If the temperature is lower than 0 ° C, melt extrusion of the polymer becomes difficult. On the other hand, if the spinning temperature exceeds 300 ° C, thermal decomposition of the polymer becomes remarkable and high-strength fibers cannot be obtained. The total draw ratio at the time of drawing the undrawn yarn depends on the strength level of the target short fiber, but is usually 2.0 to 4.0 times, whereby the tensile strength of 3.0 g / denier or more is obtained. Having short fibers.

Separately, cellulosic short fibers are prepared. The cellulosic short fibers used in the present invention are mainly natural fibers such as cotton and hemp as described above, and various types of rayon fibers and chemical fibers made of natural products such as chitin. When high mechanical strength and quality are required, it is better to use natural fibers mainly composed of cottons rather than rayon-based regenerated fibers.

Next, the obtained biodegradable staple fiber and cellulosic staple fiber are mixed in the ratio described above, and carded using a carding machine to produce a card web. A heat bonding process is performed to partially heat bond the constituent fibers. When performing the partial heat bonding, a known method can be adopted. For example, a method in which the web is passed between a roller composed of a heated embossing roller and a metal roller having a smooth surface, a method using a hot air drying device, or a method using an ultrasonic fusion device.
When the fibers existing in the emboss pattern portion are partially thermally bonded to each other by using the heated emboss roller, the pressure contact area ratio of the emboss roller is set to 5 to 50%, and if the pressure contact area ratio is less than 5%. The mechanical strength of the nonwoven fabric is reduced due to the small number of fusion zones, and good dimensional stability cannot be obtained. On the other hand, if the pressed area ratio exceeds 50%, the nonwoven fabric becomes rigid and loses its flexibility. , Neither is preferred. In addition, the temperature of the roller is usually preferably lower by about 10 to 20 ° C. than the melting point of the thermoplastic polymer having biodegradability. A nonwoven fabric having excellent mechanical strength and dimensional stability and high flexibility can be obtained.
The emboss pattern when using a hot emboss roller is
There is no particular limitation as long as the pressed area ratio is within the range of 5 to 50%, and the shape is round, elliptical, rhombic, triangular, T
Any shape such as a letter shape or a well shape may be used. When the fibers are partially thermally bonded to each other at the crossing points of the fibers using a hot-air drying device, the processing temperature depends on the processing time, but it is usually 5 points higher than the melting point of the biodegradable thermoplastic polymer. ~ 15
It is preferable to set the temperature to about lower by about ° C. The partial heat bonding using a hot embossing roller, a hot air drying device, or an ultrasonic fusing device, for example, may be a continuous process or a separate process.

[0015]

The biodegradable short-fiber nonwoven fabric of the present invention has the above-mentioned constitution, has biodegradability, moderate hydrophilicity and hydrophobicity, and has not only a dry condition but also a water absorbing / wetting condition. It has excellent mechanical strength characteristics and dimensional stability under conditions, and this nonwoven fabric has excellent mechanical strength characteristics and dimensional stability not only under dry conditions but also under water-absorbing and wet conditions. In general, hydrophobic biodegradable thermoplastic fiber and hydrophilic cellulosic fiber with little decrease in strength and excellent dimensional stability under water-absorbing / wetting conditions have uniform partial thermal bonding points between the fibers. This is considered to be due to the formation of a three-dimensional structure in the nonwoven fabric.

[0016]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples, the measurement of each characteristic value was performed by the following method. Melting point (° C): Differential scanning calorimeter DS manufactured by PerkinElmer
Measured at a heating rate of 20 ° C / min using C-2 type,
The temperature at which an extreme value was obtained in the obtained melting endothermic curve was defined as the melting point. Melt flow rate value (g / 10 min): ASTM D1
238 (L). Tensile strength of short fiber (g / denier): JIS-L-10
The measurement was carried out according to the method described in No. 13. KGSM tensile strength (kg) of nonwoven fabric: JIS-L-10
The measurement was carried out according to the method described in 96A. That is, ten sample pieces each having a sample length of 10 cm and a sample width of 5 cm were prepared, and a constant-speed elongation type tensile tester (Tensilon UTM manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the longitudinal direction of the nonwoven fabric.
−4-1-100), elongate at a tensile speed of 10 cm / min, convert the average value of the obtained breaking load value (kg) into a basis weight of 100 g / m ^2, and convert the KGSM tensile strength (k
g). Area shrinkage (%): A plurality of sample pieces each having a sample length and a sample width of 25 cm were prepared, and each sample piece was subjected to wet / dry processing three times. The processing conditions were a wet processing temperature of room temperature, a processing time of 30 minutes, a drying processing temperature of room temperature, and a processing time of 24 hours. At this time, the area S1 of the sample piece before the wet / dry processing and the area S2 of the sample piece after the third wet / dry processing were obtained, and the average value calculated from the obtained S1 and S2 by the following equation (1) was calculated. The area shrinkage rate (%) was used. Area shrinkage (%) = [1− (S2 / S1)] × 100 (1)

Example 1 A polyethylene succinate chip having a melting point of 102 ° C. and a melt flow rate of 5 g / 10 min was melted and passed through a spinneret having 36 spinning holes having a diameter of 0.5 mm at a spinning temperature of 230 ° C. Melt spinning, spun yarn at a temperature of 20
After cooling using a cooling air stream of ° C., an oil agent was applied and the film was once wound at a winding speed of 1000 m / min to obtain an undrawn yarn. Next, a total draw ratio of 3.2 was applied to the obtained undrawn yarn.
Is subjected to one-stage hot drawing using a heating roll at a temperature of 60 ° C., and a mechanical crimp of 18 pieces / 25 mm is given to the obtained drawn yarn using a stuffing box, and the length is 51 mm.
Then, short fiber cotton having a single fiber fineness of 2.2 denier and a tensile strength of 3.2 g / denier was obtained.

Next, 50% by weight of the obtained short-fiber cotton and 50% by weight of cotton (bleached cotton) having a length of 28 mm and a single-fiber fineness of 1.5 denier are mixed, and the resulting mixture is mixed using a carding machine. A card web having a basis weight of 40 g / m ² was prepared by carding, and the obtained card web was passed through an embossing roll heated to a temperature of 90 ° C. and having a pressed area ratio of 15% and a smooth roll having the same temperature. The two were partially heat-bonded to each other to obtain a nonwoven fabric. The obtained nonwoven fabric has a KGSM tensile strength of 4.2 kg / 5 cm in the longitudinal direction, 2.6 kg / 5 cm in the transverse direction,
The area shrinkage was 1.9%, and the mechanical strength and dimensional stability were excellent. When the nonwoven fabric was buried in the soil for two months and then taken out and observed, it was confirmed that the nonwoven fabric had disappeared and had excellent biodegradability.

[0019]

[0020]

[0021]

As described above , the biodegradable nonwoven fabric of the present invention comprises 95 to 5% by weight of short fibers comprising a biodegradable thermoplastic aliphatic polyester polymer and 5 to 9 cellulose short fibers.
5% by weight, and the constituent fibers are partially thermally bonded to each other, and have biodegradability, moderate hydrophilicity and hydrophobicity, and not only under dry conditions but also under water absorption. -It has excellent mechanical strength even under wet conditions, and has extremely small shrinkage even during repeated drying and wetting, and has excellent dimensional stability. Further, since this nonwoven fabric has excellent thermal adhesiveness, sewing is not required for commercialization.

The nonwoven fabric of the present invention can be used as a material for agricultural, horticultural and civil engineering materials used outdoors, in particular, vegetation sheets,
It is suitable as a material for sowing sheets, seed tapes and nursery beds. That is, conventional rayon-based nonwoven fabrics and various other biodegradable nonwoven fabrics have poor dimensional stability due to the fact that the nonwoven fabric itself shrinks greatly during repeated drying and wetting, resulting in poor dimensional stability. The nonwoven fabric of the present invention has good dimensional stability as described above, but has a problem that the grounding rate is low due to the partial rise and the grounding rate is lowered, and the seed germination rate is lowered. Thus, the germination rate of the seed can be improved. Moreover,
In the nonwoven fabric of the present invention, the nonwoven fabric itself is decomposed by enzymes released mainly from the microorganisms in the soil from the ground contact surface with the ground, and finally disappears completely as new plants germinate and grow. Is returned to the soil, which is beneficial from the viewpoint of protecting the natural environment.

The nonwoven fabric of the present invention is also suitable as a material for living-related materials, particularly as a material for living-related materials used under wet conditions such as wet wipers. In other words, conventional rayon-based nonwoven fabrics and various other biodegradable nonwoven fabrics have the problem that the mechanical strength of the nonwoven fabric is low and hydrophilic, so that the mechanical strength of the nonwoven fabric during water absorption / wetting is significantly reduced. The constructed biodegradable nonwoven fabric has a problem that it has poor hydrophilicity and cannot be put to practical use in application fields where a certain water retention capacity is required. However, the nonwoven fabric of the present invention has a mechanical strength. And water retention capacity, and can be used in application fields used under wet conditions such as wet wipers that require a certain level of water retention capacity. It is also useful from the viewpoint of resource reuse.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-146754 (JP, A) JP-A-5-214648 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D04H 1/00-18/00 EPAT (QUESTEL) WPI / L (QUESTEL)

Claims (2)

(57) [Claims] 1. A blend of 95 to 5% by weight of short fibers made of a biodegradable thermoplastic aliphatic polyester-based polymer and 5 to 95% by weight of cellulosic short fibers. Partially heat-bonded, wherein the aliphatic polyester-based polymer is poly (α-hydroxy acid)
A polymer consisting of polyglycolic acid or polylactic acid or a copolymer thereof, or poly-3-hydroxybutyrate, poly-3-hydroxycaprolate, poly-3
-Hydroxyheptanoate, poly-3-hydroxyoctanoate, and poly (β-hydroxyalkanoate), which is a copolymer of these with poly-3-hydroxyvalerate or poly-4-hydroxybutyrate, or glycol And a polymer obtained by condensation polymerization of dicarboxylic acid and polyethylene oxalate, polyethylene succinate, polybutylene oxalate, polybutylene succinate, or a copolymer thereof, and having a melting point of 100 ° C. A biodegradable short fiber nonwoven fabric characterized by the above. 2. A cellulosic claim 1 Symbol placement biodegradable staple fiber nonwoven staple fiber is cotton.